Frame loss measurement apparatus and method for multicast service traffic

ABSTRACT

An apparatus and method for measuring frame loss in multicast service traffic are provided. The method of measuring frame loss includes: counting the number of data frames of a predetermined multicast service flowing into an object network of frame loss measurement; counting the number of data frames of the predetermined multicast service flowing out of the network; and measuring frame loss by comparing the counted number of incoming frames and the counted number of outgoing frames. According to the method and apparatus, in a multicast service environment which is dynamically changing, frame loss of a predetermined multicast service can be conveniently and easily measured.

TECHNICAL FIELD

The present invention relates to a frame loss measurement apparatus andmethod, and more particularly, to an apparatus and method for measuringframe loss of a predetermined multicast service when operation,administration and maintenance (OAM) functions required for a metroEthernet service or carrier Ethernet service are performed in amultipoint connection environment.

BACKGROUND ART

A metro Ethernet service or carrier Ethernet service is a service which,when there are a plurality of geographically dispersed privatecommunication networks of a user, supports a service provider so thatthe service provider can connect the plurality of private communicationnetworks by using public communication networks, thereby creating theimpression of a single local area network (LAN).

These Ethernet service technologies aim at guaranteeing quality ofservice (QoS) and high level reliability, and in order to standardizetechnologies for this aim, international standardization bodies such asthe Institute of Electrical and Electronics Engineers (IEEE), MEF, andthe ITU Telecommunication Standardization Sector (ITU-T), are carryingout standardization related to the Ethernet OAM.

One of the major functions of the Ethernet OAM is measurement ofperformance, and in particular, measurement of frame loss is animportant function. At a point through which frames are flowing into anetwork, the number of frames flowing into the network is counted, andat a point through which frames are flowing out, the number of framesflowing out of the network is counted, and then, by comparing the twocounted values, the degree of frame loss is calculated.

Though there are standardized methods of measuring frame loss in anend-to-end connection, it is difficult to accurately measure frame lossfor a multipoint connection. In the case of unicast in which trafficflows in through one point, travels through an internal network, andthen flows out through one of many points, an input end does not knowwith the destination address information of an Ethernet frame, throughwhich output end the traffic flows out.

Exceptionally, when a fixed path for each point is provided as a fullmesh form by using a circuit switch type technology, and if an Ethernetframe flows into a network, a fixed path connected to the destination ofthe Ethernet frame is determined at the input end. However, the fixedpath technology in the form of a full mesh form is used in a limitedrange, and when multicast traffic should be transferred, it still cannotbe known through which output end traffic will flow out. In addition,when an Ethernet frame arrives at an output end, it is difficult todetermine according to conventional Ethernet service technology, throughwhich input end the frame has flowed in.

In the case of multicast traffic, the traffic flows into a networkthrough one or a small number of points, is copied inside the network,and flows out of the network through multiple points. Through whichports the frames of the multicast traffic are output after being copiedat a switch in the network is determined by a multicast traffic controlprotocol such as an Internet group management protocol (IGMP). Sinceswitches participating in a predetermined multicast service and theports of the switches are determined by a multicast control protocol, anincoming end through which traffic flows in should know which switchesand/or ports are participating in a predetermined multicast service, inorder to measure frame loss.

However, the participating in and seceding from a multicast service isvery dynamic, and informing an incoming end of each change inparticipation in the multicast service is very expensive. Accordingly,in a multipoint connection environment, instead of accurate measurementof frame loss based on counting of data frames, the number of OAM frameswhich are generated and discarded on the border of a network is counted,and used as an approximate value of the frame loss measurement value ofthe network. However, this method provides only a rough frame loss ofthe whole network.

One of the important functions provided by a multipoint connectionenvironment is facilitating implementation of a multicast service. Withthe introduction of multimedia services such as Internet protocoltelevision (IPTV) and voice on demand (VOD), accurate measurement offrame loss in a predetermined multicast service has become increasinglyimportant. For example, frame loss affects the picture quality of video,and a network provider or operator should necessarily be able toaccurately measure frame loss in order to maintain a high level of aservice level agreement for a predetermined premium multicast service.

DETAILED DESCRIPTION OF THE INVENTION DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating a network in which a method ofmeasuring frame loss is implemented according to an embodiment of thepresent invention;

FIG. 2 is a block diagram illustrating an apparatus for measuring frameloss according to an embodiment of the present invention;

FIG. 3 is a block diagram illustrating an apparatus for measuring frameloss according to another embodiment of the present invention;

FIG. 4 is a block diagram illustrating a structure for counting thenumber of outgoing frames in an apparatus for measuring frame lossaccording to an embodiment of the present invention;

FIG. 5 is a diagram illustrating a frame used for a method of measuringframe loss as a loss measurement request or response frame according toan embodiment of the present invention;

FIG. 6 is a flowchart illustrating a method of measuring frame loss in anetwork, according to an embodiment of the present invention;

FIG. 7 is a flowchart illustrating a method of measuring frame loss atan end point of a network through which frames are flowing in, accordingto an embodiment of the present invention; and

FIG. 8 is a flowchart illustrating a method of measuring the number ofoutgoing frames in order to measure frame loss in a network, accordingto an embodiment of the present invention.

TECHNICAL PROBLEM

The present invention provides an apparatus and method capable ofaccurately measuring frame loss without prior information on changes ina traffic path of a multicast service or information on from which nodetraffic is output.

Technical Solution

According to an aspect of the present invention, there is provided anapparatus for measuring frame loss, including: an incoming framecounting unit counting the number of data frames of a predeterminedmulticast service flowing into an object network of frame lossmeasurement; an outgoing frame counting unit counting the number of dataframes of the predetermined multicast service flowing out of thenetwork; and a loss measurement unit measuring frame loss, by comparingthe number of the data frames counted by the outgoing frame countingunit and the number of the data frames counted by the incoming framecounting unit.

According to an aspect of the present invention, there is provided amethod of measuring frame loss, including: counting the number of dataframes of a predetermined multicast service flowing into an objectnetwork of frame loss measurement; counting the number of data frames ofthe predetermined multicast service flowing out of the network; andmeasuring frame loss, by comparing the number of data frames flowinginto the network and the number of data frames flowing out of thenetwork.

According to an aspect of the present invention, there is provided anapparatus for measuring frame loss, including: an incoming framecounting unit counting the number of data frames of a predeterminedmulticast service flowing into an object network of frame lossmeasurement; a frame transmission and reception unit receiving a lossmeasurement response frame comprising the number of data frames of thepredetermined multicast service which are flowing out of the network;and a loss measurement unit measuring frame loss of the predeterminedmulticast service based on the number of data frames flowing into thenetwork and the number of data frames flowing out of the network.

According to an aspect of the present invention, there is provided amethod of measuring frame loss, including: counting the number of dataframes of a predetermined multicast service flowing into an objectnetwork of frame loss measurement; receiving a loss measurement responseframe comprising an the number of data frames of the predeterminedmulticast service which are flowing out of the network; and measuringframe loss of the predetermined multicast service based on the number ofdata frames flowing into the network and the number of data framesflowing out of the network.

According to an aspect of the present invention, there is provided anapparatus for measuring frame loss, including: a request frame receptionunit receiving a loss measurement request frame of a predeterminedmulticast service from an object network of frame loss measurement; anoutgoing frame counting unit counting the number of data frames of thepredetermined multicast service which are flowing out of the network;and a response frame transmission unit generating a loss response framecomprising the number of data frames flowing out of the network, andtransmitting the loss response frame to the destination address of theloss measurement request frame.

According to an aspect of the present invention, there is provided amethod of measuring frame loss, including: receiving a loss measurementrequest frame of a predetermined multicast service from an objectnetwork of frame loss measurement; counting the number of data frames ofthe predetermined multicast service which are flowing out of thenetwork; and generating a loss response frame comprising the number ofdata frames flowing out of the network, and transmitting the lossresponse frame to the destination address of the loss measurementrequest frame.

Advantageous Effects

According to the present invention, in a multicast service environmentof an Ethernet network, frame loss of a predetermined multicast servicecan be accurately and conveniently measured. In particular, the frameloss can be measured without prior information on a dynamically changingmulticast traffic path, and information on which end points areparticipating in the multicast service.

Best Mode

According to an aspect of the present invention, there is provided anapparatus for measuring frame loss, including: an incoming framecounting unit counting the number of data frames of a predeterminedmulticast service flowing into an object network of frame lossmeasurement; an outgoing frame counting unit counting the number of dataframes of the predetermined multicast service flowing out of thenetwork; and a loss measurement unit measuring frame loss, by comparingthe number of the data frames counted by the outgoing frame countingunit and the number of the data frames counted by the incoming framecounting unit.

According to an aspect of the present invention, there is provided amethod of measuring frame loss, including: counting the number of dataframes of a predetermined multicast service flowing into an objectnetwork of frame loss measurement; counting the number of data frames ofthe predetermined multicast service flowing out of the network; andmeasuring frame loss, by comparing the number of data frames flowinginto the network and the number of data frames flowing out of thenetwork.

According to an aspect of the present invention, there is provided anapparatus for measuring frame loss, including: an incoming framecounting unit counting the number of data frames of a predeterminedmulticast service flowing into an object network of frame lossmeasurement; a frame transmission and reception unit receiving a lossmeasurement response frame comprising the number of data frames of thepredetermined multicast service which are flowing out of the network;and a loss measurement unit measuring frame loss of the predeterminedmulticast service based on the number of data frames flowing into thenetwork and the number of data frames flowing out of the network.

According to an aspect of the present invention, there is provided amethod of measuring frame loss, including: counting the number of dataframes of a predetermined multicast service flowing into an objectnetwork of frame loss measurement; receiving a loss measurement responseframe comprising an the number of data frames of the predeterminedmulticast service which are flowing out of the network; and measuringframe loss of the predetermined multicast service based on the number ofdata frames flowing into the network and the number of data framesflowing out of the network.

According to an aspect of the present invention, there is provided anapparatus for measuring frame loss, including: a request frame receptionunit receiving a loss measurement request frame of a predeterminedmulticast service from an object network of frame loss measurement; anoutgoing frame counting unit counting the number of data frames of thepredetermined multicast service which are flowing out of the network;and a response frame transmission unit generating a loss response framecomprising the number of data frames flowing out of the network, andtransmitting the loss response frame to the destination address of theloss measurement request frame.

According to an aspect of the present invention, there is provided amethod of measuring frame loss, including: receiving a loss measurementrequest frame of a predetermined multicast service from an objectnetwork of frame loss measurement; counting the number of data frames ofthe predetermined multicast service which are flowing out of thenetwork; and generating a loss response frame comprising the number ofdata frames flowing out of the network, and transmitting the lossresponse frame to the destination address of the loss measurementrequest frame.

Mode of the Invention

FIG. 1 is a diagram illustrating a network in which a method ofmeasuring frame loss is implemented according to an embodiment of thepresent invention.

Referring to FIG. 1, the traffic of a predetermined multicast serviceflows into an object network of frame loss measurement (hereinafter willbe referred to as a “network”) 100 through node A and flows out throughnodes B, D, and F. The predetermined multicast service traffic which isthe object of frame loss measurement arrives at service users directlyfrom the network 100 or through another network.

As time passes by, a new user joins in the multicast service or secedesfrom (stops receiving) the multicast service, thereby changing nodesthrough which the predetermined multicast service traffic which hasflowed in the network 100 flows out of the network 100.

For example, it is assumed that predetermined multicast service trafficwhich has flowed in through a current node A is transferred throughnodes B, D, and F. Then, after a predetermined time elapses, if nomulticast user connected to the node B exists, and a new service userreceives the multicast traffic through the node E, the predeterminedmulticast service traffic is transferred to the nodes D, E, and F.

Thus, participating in and seceding from reception of a predeterminedmulticast service is performed according to free intentions of servicesusers, and in this case, participating in and seceding from apredetermined multicast service is automatically performed through amulticast control protocol (for example, an Internet group managementprotocol (IGMP)). Also inside the network 100, traffic is copied innodes which are determined by the multicast control protocol, anddistributed, and the number of nodes participating in the transferringof the traffic changes whenever necessary.

According to the present invention, measurement of loss of predeterminedmulticast frames transferred through this kind of network is performedat the boundary of the network. For example, referring to FIG. 1, frameloss is measured at boundary points of the network 100 including a point(A,G) where the node A is connected to the node C, and also includepoints (B,H), (C,H), (D,L), (E,L), and (F,K). Hereinafter these pointswill be referred to as end points.

FIG. 2 is a block diagram illustrating an apparatus for measuring frameloss according to an embodiment of the present invention.

Referring to FIG. 2, the apparatus for measuring frame loss according tothe current embodiment includes an incoming frame counting unit 200, anoutgoing frame counting unit 210, and a loss measurement unit 220.

The incoming frame counting unit 200 counts the number of frames of apredetermined multicast service which flow into an object network offrame loss measurement. For example, in the case illustrated in FIG. 1,if frames of a predetermined multicast service are flowing into thenetwork 100 through the node A, the number of frames which are flowinginto the node G from the node A is counted at the end point (A,G).

The outgoing frame counting unit 210 counts the number of frames of thepredetermined multicast service which flow out of the network. Forexample, in the case illustrated in FIG. 1, if frames of thepredetermined multicast service are flowing out of the network 100through the nodes B, D, and F, the number of frames which are flowingout of the network 100 is counted at each of the end points (B,H),(D,L), and (F,K).

The loss measurement unit 220 measures the frame loss based on thenumber of the incoming frames of the predetermined multicast servicecounted by the incoming frame counting unit 200 and the number of theoutgoing frames of the predetermined multicast service counted by theoutgoing frame counting unit 210.

FIG. 3 is a block diagram illustrating an apparatus for measuring frameloss according to another embodiment of the present invention.

Referring to FIG. 3, the apparatus for measuring frame loss according tothe current embodiment of the present invention includes an incomingframe counting unit 300, a frame transmission and reception unit 310,and a loss measurement unit 340. The frame transmission and receptionunit 310 further includes a request frame transmission unit 320 and aresponse frame reception unit 330. In the apparatus for measuring frameloss according to the current embodiment, measurement is performed atthe boundary of a network. For example, in the case illustrated in FIG.1, measurement is performed at the end points, including the end pointbetween the node A and the node G.

The incoming frame counting unit 300 counts the number of frames of apredetermined multicast service which are flowing into an object networkof frame loss measurement in a predetermined time period.

Immediately after the number of incoming frames is counted by theincoming frame counting unit 300, the frame transmission and receptionunit 310 generates a loss measurement request frame, including thenumber of incoming frames, and then, multicasts the loss measurementrequest frame. Then, as responses to the loss measurement request frame,the frame transmission and reception unit 310 receives loss measurementresponse frames, including information on the number of frames of thepredetermined multicast service which are flowing out of the networkthrough each of the other end points.

More specifically, the request frame generation unit 320 generates theloss measurement request frame, including a multicast service ID, andinformation on the number of the incoming frames, and then, multicaststhe loss measurement request frame to the inside of the network. Themulticast loss measurement request frame is transferred to all other endpoints in the network.

Then, each of the end points confirms based on the multicast service IDincluded in the loss measurement request frame, whether or not the endpoint is participating in the multicast service. Then, if the end pointis participating in the multicast service, the end point sends back aloss measurement response frame, including the number of frames of thepredetermined multicast service which are flowing out of the network.The response frame reception unit 330 receives the loss measurementresponse frames transmitted by the end points.

The loss measurement request frame and the loss measurement responseframe can be implemented and used in a variety of structures, and oneembodiment is illustrated in FIG. 5.

Referring back to FIG. 3, the loss measurement unit 340 measures theframe loss of the predetermined multicast service, based on the numberof the incoming frames of the predetermined multicast service counted bythe incoming frame counting unit 300, and the number of the outgoingframes of the predetermined multicast service recognized by the frametransmission and reception unit 310. For example, the loss measurementunit 340 can learn the frame loss from the difference between the numberof the outgoing frames and the number of the incoming frames.

When the number of incoming frames and the number of outgoing frames aremeasured in each of a plurality of predetermined time periods, the lossmeasurement unit 340 can obtain a frame loss according to Equation 1below:

Frame loss=|the number of incoming frames (t _(c))−the number ofincoming frames (t _(p))|−|the number of outgoing frames (t _(c))−thenumber of outgoing frames (t _(p))|  Equation (1)

Here, t indicates a time, and t_(c)>t_(p).

FIG. 4 is a block diagram illustrating a structure for counting thenumber of outgoing frames in an apparatus for measuring frame lossaccording to an embodiment of the present invention.

Referring to FIG. 4, the apparatus for measuring frame loss according tothe current embodiment of the present invention includes a request framereception unit 400, an outgoing frame counting unit 410, and a responseframe transmission unit 420.

If a loss measurement request frame, including a multicast service ID,is received, the request frame reception unit 400 confirms whether ornot the apparatus is participating in a predetermined multicast servicecorresponding to the multicast service ID. If the apparatus is notparticipating in the predetermined multicast service, the request framereception unit 400 discards the received loss measurement request frame.

If the request frame reception unit 400 is participating in thepredetermined multicast service, the outgoing frame counting unit 410identifies the number of outgoing frames of the predetermined multicastservice which have flowed out of the network.

The response transmission unit 420 generates a loss measurement responseframe, including the number of the outgoing frames, and transmits theloss measurement response frame to the source address of the lossmeasurement request frame.

FIG. 5 is a diagram illustrating a frame used for a method of measuringframe loss as a loss measurement request or response frame, according toan embodiment of the present invention.

Referring to FIG. 5, the loss measurement request frame and lossmeasurement response frame are based on an identical Ethernet OAM framedefined in the ITU-T. The OAM frame structure illustrated in FIG. 5 isjust one embodiment of the present invention, and the positions andsizes of the fields can be changed in a variety of ways and usedaccording to embodiments, and other types of format of otherstandardization organizations can also be used. Referring to FIG. 5, theloss measurement request or response frame according to the currentembodiment of the present invention includes a destination Ethernetaddress field 500, a source Ethernet address field 505, a multicastservice ID field 550, and a TxFCf field 540.

First, the loss measurement request frame will be explained.

The destination Ethernet address field 500 is a 6-byte field, andincludes an address value which designates all end points of an objectnetwork of frame loss measurement as destinations. This address value isnot the multicast address of the network, and is a value defined as aMulticast Class 1 in an Ethernet OAM related standard of the ITU-T.

The source Ethernet address field 505 is a 6-byte field, and indicatesthe Ethernet address of an end point through which frames of themulticast service which is the object of the measurement flow.

The multicast service ID field 550 indicates the multicast service whichis the object of the measurement. For example, in the multicast serviceID field 550, the IP address value of the multicast group which is theobject of the measurement may be recorded.

In the TxFCf field 540, the number of incoming frames is recorded.

Also, there are fields that do not directly relate to the presentinvention, including a VLAN Tag and other option field 51 0, an OAMEtherType field 560, an MEL field 515, a version field 520, an OpCodefield 515, a Flags field 530, and a TLV Offset field 535.

The VLAN tag and other option field 510 varies with respect totechnologies forming a network, and may be omitted or formed by manyfields. The size of the VLAN tag and other option field 510 is variable.If a technology forming a network is based on IEEE 802.1Q, VLAN Taginformation is recorded in the VLAN tag and other option field 510.

The OAM EtherType field 560 is a 2-byte field, and includes a valueindicating that information after the OAM EtherType field 560 is anEthernet OAM PDU. The MEL field 515 includes a 3-bit maintenance entitygroup level value, and indicates the level of an OAM object area. Theversion field 520 is a 1-byte field in which the version value of an OAMmessage is recorded. The size of each of the OpCode field 525 and theFlags field 530 is 1 byte. The values recorded in the OpCode field 525and the Flags field 530 indicate whether the current frame is a lossmeasurement request frame for measuring frame loss of a multicastservice.

The TLV Offset field 535 is a 1-byte field used to indicate the startposition of a TLV field. In the case illustrated in FIG. 5, there is noseparate TLV field, and therefore the TLV Offset field 535 has a valueof 12. The End TLV field 55 is a 1-byte field always having a value of0, and indicates that a TLV field ends.

Next, the loss measurement response frame will be explained.

The destination Ethernet address field 500 is a 6-byte frame, and thevalue of the source Ethernet address field of the loss measurementrequest frame is copied and recorded in the destination Ethernet addressfield 500.

The source Ethernet address field 505 is a 6-byte field, and containsthe Ethernet address of an end point which generates and transmits theloss measurement response frame.

The multicast service ID field 550 indicates the multicast service whichis the object of the measurement, and is the same as the value expressedin the loss measurement request frame. When the IP address value of amulticast group is used as the multicast service ID, the size of the IPaddress is 4 bytes long.

The TxFCf field 540 is a 4-byte field, and the value of the TxFCF fieldof the loss measurement request frame is copied and recorded in theTxFCf field 540.

An RxFCf field 545 is a 4-byte field, and when the loss measurementrequest frame is received, the number of frames which have flowed out ofthe current network is recorded in the RxFCf field 545.

Other fields are the same as described above in relation to the lossmeasurement request frame.

FIG. 6 is a flowchart illustrating a method of measuring frame loss in anetwork, according to an embodiment of the present invention.

Referring to FIG. 6, the number of data frames of a predeterminedmulticast service which are following into an object network of frameloss measurement is counted in operation S600. Then, the number of dataframes of the predetermined multicast service which are flowing out ofthe network is counted in operation S610. The frame loss of thepredetermined multicast service is measured based on the two countingresults, i.e., the number of the incoming frames and the number of theoutgoing frames, in operation S620.

FIG. 7 is a flowchart illustrating a method of measuring frame loss atan end point of a network through which frames are flowing in, accordingto an embodiment of the present invention.

Referring to FIG. 7, an end point positioned at the boundary of anetwork through which data frames of a predetermined multicast serviceare flowing into the network, the number of data frames which areflowing into the network in operation S700. The end point generates aloss measurement request frame including a multicast service ID and thenumber of the incoming frames in operation S710, and multicasts theframe to the inside of the network in operation S720.

If the multicast loss measurement request frame is received, each of allother end points positioned at other locations of the boundary of thenetwork, determines based on the multicast service ID, whether or notthe end point is participating in the multicast service. If it isdetermined that the end point is participating in the multicast service,the end point generates a loss measurement response frame, includinginformation on the number of the outgoing frames which have flowed outof the network, and sends the frame back to the end point whichtransmitted the loss measurement request frame, in operation S730.

The end point which receives the loss measurement response framemeasures the frame loss of the predetermined multicast service, based onthe difference between the number of the incoming frames and the numberof the outgoing frames in operation S740.

FIG. 8 is a flowchart illustrating a method of measuring the number ofoutgoing frames in order to measure frame loss in a network, accordingto an embodiment of the present invention.

Referring to FIG. 8, an end point positioned at the boundary of anetwork through which frames are flowing out of the network receives aloss measurement request frame from an end point positioned at theboundary of the network through which frames are flowing into thenetwork, in operation S800.

The end point which receives the loss measurement request frameconfirms, based on a multicast service ID included in the lossmeasurement request frame, whether or not the end point is participatingin the multicast service, in operation S810.

If it is determined that the end point is participating in the multicastservice, the end point generates a loss measurement response frame,including the number of the outgoing data frames of the predeterminedmulticast service corresponding to the multicast service ID which haveflowed out of the network, in operation S820. Then, the end pointtransmits the generated loss measurement response frame to the end pointwhich transmitted the loss measurement request frame, in operation S830.

The present invention can also be embodied as computer readable codes ona computer readable recording medium. The computer readable recordingmedium is any data storage device that can store data which can bethereafter read by a computer system. Examples of the computer readablerecording medium include read-only memory (ROM), random-access memory(RAM), CD-ROMs, magnetic tapes, floppy disks, optical data storagedevices, and carrier waves (such as data transmission through theInternet). The computer readable recording medium can also bedistributed over network coupled computer systems so that the computerreadable code is stored and executed in a distributed fashion.

While the present invention has been particularly shown and describedwith reference to exemplary embodiments thereof, it will be understoodby those of ordinary skill in the art that various changes in form anddetails may be made therein without departing from the spirit and scopeof the present invention as defined by the following claims. Thepreferred embodiments should be considered in descriptive sense only andnot for purposes of limitation. Therefore, the scope of the invention isdefined not by the detailed description of the invention but by theappended claims, and all differences within the scope will be construedas being included in the present invention.

1. An apparatus for measuring frame loss, comprising: an incoming framecounting unit counting the number of data frames of a predeterminedmulticast service flowing into an object network of frame lossmeasurement; an outgoing frame counting unit counting the number of dataframes of the predetermined multicast service flowing out of thenetwork; and a loss measurement unit measuring frame loss, by comparingthe number of the data frames counted by the outgoing frame countingunit and the number of the data frames counted by the incoming framecounting unit.
 2. A method of measuring frame loss, comprising: countingthe number of data frames of a predetermined multicast service flowinginto an object network of frame loss measurement; counting the number ofdata frames of the predetermined multicast service flowing out of thenetwork; and measuring frame loss, by comparing the number of dataframes flowing into the network and the number of data frames flowingout of the network.
 3. An apparatus for measuring frame loss,comprising: an incoming frame counting unit counting the number of dataframes of a predetermined multicast service flowing into an objectnetwork of frame loss measurement; a frame transmission and receptionunit receiving a loss measurement response frame comprising the numberof data frames of the predetermined multicast service which are flowingout of the network; and a loss measurement unit measuring frame loss ofthe predetermined multicast service based on the number of data framesflowing into the network and the number of data frames flowing out ofthe network.
 4. The apparatus of claim 3, wherein the frame transmissionand reception unit comprises: a request frame transmission unitgenerating and transmitting a loss measurement request frame, comprisinga source address and a multicast service ID indicating the predeterminedmulticast service, setting all nodes positioned at the boundary of thenetwork as destination addresses; and a response frame reception unitreceiving the loss measurement response frame, comprising the number ofdata frames of the multicast service which are flowing out of thenetwork, from each of a plurality of nodes participating in thepredetermined multicast service from among the nodes receiving the lossmeasurement request frame.
 5. The apparatus of claim 4, wherein therequest frame transmission unit generates the loss measurement requestframe which further comprises the number of data frames flowing into thenetwork, and the response frame reception unit receives the lossmeasurement response frame comprising the number of data frames flowinginto the network and the number of data frames flowing out of thenetwork, and the loss measurement unit measures the frame loss based onthe difference between the number of data frames flowing into thenetwork and the number of data frames flowing out of the networkincluded in the loss measurement response frame.
 6. The apparatus ofclaim 3, wherein each of the loss measurement request frame and the lossmeasurement response frame is an operation, administration andmaintenance (OAM) frame.
 7. The apparatus of claim 3, wherein the frametransmission and reception unit transmits the loss measurement requestframe and receives the loss response frame in each of a plurality ofpredetermined time periods, and the loss measurement unit measures theframe loss based on the number of data frames which are flowing into thenetwork during the predetermined time interval and the number of dataframes which are flowing out of the network during the predeterminedtime period.
 8. A method of measuring frame loss, comprising: countingthe number of data frames of a predetermined multicast service flowinginto an object network of frame loss measurement; receiving a lossmeasurement response frame comprising an the number of data frames ofthe predetermined multicast service which are flowing out of thenetwork; and measuring frame loss of the predetermined multicast servicebased on the number of data frames flowing into the network and thenumber of data frames flowing out of the network.
 9. The method of claim8, wherein the receiving of the loss measurement response framecomprises: generating and transmitting a loss measurement request frame,comprising a source address and a multicast service ID indicating thepredetermined multicast service, setting all nodes positioned at theboundary of the network as destination addresses; and receiving the lossmeasurement response frame, comprising the number of data frames of themulticast service which are flowing out of the network, from each of aplurality of nodes participating in the predetermined multicast servicefrom among the nodes receiving the loss measurement request frame. 10.The method of claim 8, wherein the receiving of the loss measurementresponse frame comprises transmitting the loss measurement request frameand receiving the loss response frame in each of a plurality ofpredetermined time periods, and the measuring of the frame losscomprises measuring the frame loss based on the number of data frameswhich are flowing into the network during the predetermined time periodand the number of data frames which are flowing out of the networkduring the predetermined time period.
 11. An apparatus for measuringframe loss, comprising: a request frame reception unit receiving a lossmeasurement request frame of a predetermined multicast service from anobject network of frame loss measurement; an outgoing frame countingunit counting the number of data frames of the predetermined multicastservice which are flowing out of the network; and a response frametransmission unit generating a loss response frame comprising the numberof data frames flowing out of the network, and transmitting the lossresponse frame to the destination address of the loss measurementrequest frame.
 12. The apparatus of claim 11, wherein the outgoing framecounting unit transmits the loss response frame if it is determined,based on a multicast ID included in the loss measurement request frameand indicating the predetermined multicast service, that the outgoingframe counting unit is participating in the multicast service.
 13. Theapparatus of claim 11, wherein the request frame reception unit receivesthe loss measurement request frame, comprising the number of data framesof the predetermined multicast service which are flowing into thenetwork, and the response frame transmission unit transmits the lossmeasurement response frame, comprising the number of data frames flowinginto the network and the number of data frames flowing out of thenetwork.
 14. A method of measuring frame loss, comprising: receiving aloss measurement request frame of a predetermined multicast service froman object network of frame loss measurement; counting the number of dataframes of the predetermined multicast service which are flowing out ofthe network; and generating a loss response frame comprising the numberof data frames flowing out of the network, and transmitting the lossresponse frame to the destination address of the loss measurementrequest frame.
 15. The method of claim 14, wherein in the counting ofthe number of data frames flowing out of the network, if it isdetermined based on a multicast ID included in the loss measurementrequest frame and indicating the predetermined multicast service, thatthe multicast service is participated in, the loss response frame istransmitted.
 16. The method of claim 14, wherein the loss measurementrequest frame comprises the number of data frames of the predeterminedmulticast service which are flowing into the network, and the lossmeasurement response frame comprises the number of data frames flowinginto the network and the number of data frames flowing out of thenetwork.